Heat-exchange apparatus



HEAT EXCHANGE APPARATUS Filed April 9, 192e Patented Mayl4, 1929.

UNITED STATES PATENT OFFICE.

GREGORY D. MANTLE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO MANTLE EN- GINEERING COMPANY, lA CORPORATION OF PENNSYLVANIA.

EEATEXCHANGE APPARATUS.

Application filed .April 9, 1926. Serial No. 100,863.

rl`his invention relates to heat exchange'apparatus and more particularly to the type adapted to be used in connection with a flue chamber or the like for the purpose of utilizing the heat of combustion gases for the purpose of raising the temperature of a fluid such, forexample, as air passed through-the apparatus.

Although the most eicient form of heat exchanger is the straight counter flow type, in which the direction of iiow of the fluid passing through the apparatus to be heated is opposite to the direction of flow of the heating gases, this type has certain practical disadvantages which result from the fact that that part of the apparatus which is exposed to the highest temperature of the-heating gases is also the part conveying the hottest fluid to be heated with the result that the temperature of the material from which the heat exchanger is constructed at that point may be so high as to materially reduce the effective life of the structure. In view of the act that the counter ilow type of heat exchanger insures the greatest mean temperature difference between the Huid to be heated and the heating gases, this type ofapparatus takesthe greatest advantage of the convec'tedy heat but fails, Aon the other hand, to eiciently utilize the radiant heat available from sources outsidevof the heating gases such, for example, as the brick Ysetting of the associated flue chamber or the like, and this is due to the fact that such heat is most intense at the point where the heating fluid enters the apparat-us which, in a counter flow type, is alsothe point where the fluid to beheated is hottest sothat the heat transfer at this point is relatively low, due to the fact that, as stated in` Stefan-Boltzmann@ law, the rate of h'eat transfer by radiation from a hotter to a cooler body is proportional to the difference in the fourth powers of their absolute temperatures.

An object of this invention is to provide a heat exchange apparatus of such construction and arrangement that the llow of fluid to be heated through that part of the apparatus subjected to the highest temperature can be given a predetermined characteristic such, for example, as quantity flow, regardless of .the tot-a1 flow through the apparatus. A further object is to provide a device of the type set forth of such construction and arrangement as to obtainthe vtltllllot effect from the radiant heat of the associated structure and at the same time to maintain the greatest mean temperature difference between the temperature of the heating gases and that of the fluid to be heated so as to obtain the most efficient heat transfer.

These and other objects which will be apparent to those skilled in this particular art are attained by means of this invention, one formpf which is illustrated in the accompanylng drawing which shows a sectional View through a heat exchange apparatus construction in accordance with one embodiment of this invention. y

The particular embodiment of this invention which has been chosen for the purposes of illustration includes a'iuid transmitting section provided with an arrangement of con# dults or passageways through which fluid to be heated, such as air, is passed. Two conduits or passageways arer provided for transmitting separate streams of air downwardly through the heating section in a direction generally counter to the direction of flow of the heating gases through the apparatus. Each conduit has passageways extending across the section and the cross flow passageways of one conduit alternate with the similar passageways of the other conduit. A counter flow passage or conduit is provided in the lower end of the section which 1s subjected to the highest temperature and one of the streams of air' passes therethrough so as to take the utmost advantage of the radiant heat of the flue chamber or other structure with which the apparatus is associated. In effect, the two conduits are associated in parallel relation relative to each other and the separatestreams are united adjacent a common outlet.

It will, of course, be readily understood by those skilled in this art that any number of heat exchange sections, .such as that illus-f trated, can 'be arranged in spaced and parallel relationtoorm a heat exchange apparatus of any requiredsize, as for example, is disclosed in the hereinafter mentioned ap plications. E

As illustrated, an inlet 5 opens into a manifold 6 communicating with an entrance 7 to a conduit or passageway 8 through which a stream of air is directed in a generally downward direction or in a-direction which is generali counter to the direction of flow of the heatmg gases. This counter flow conduit includes a number of cross flow passageways 9 by means of which the stream of air in its downward travel is led back and forth across the line of flow of the heating gases around bailles 10 which are extended outwardly to the edge of each section so as to separate the ditlerent portions of the conduit 8 between the cross iiow passages. An opening 11 leads to an outlet duct 12 provided with a baille 13 for preventing the format-ion of dead air pockets by directing the outwardly lowin stream of air to the bottom of the outlet duct whence it flows upwardly to the outlet 14.

A second inlet 15 leads to a second counter How conduit 16 similar to the conduit 8 and provided with similar cross ilow passageways 17 which are positioned in alternate relation to the cross flow passages 9 of the first counter flow conduit 8. The second counter flow conduit 16 leads through an opening 18 to a passageway 19 through which the stream of air follows a circuit-ous route around the bailies 20 to an opening 21 leading to the outlet duct 12 below the baille 13. The latter passageway forms, in effect, a continuation of the second counter flow passage 16 and a stream of air passing through this counter flow conduit flows through the opening 18 after passing around a baille 22 which is provided for the purpose of directing the stream downwardly to the bottom of the manifold 23 outside of the conduit 18 for the purpose of preventing the formation of dead air pockets at that point. Each inlet is provided with a separately operable controlling valve 24 for the purpose of separately controlling the passage of air therethrough.

It will be apparent that the two counter h flow passages for the separate streams of air are arranged in parallel relation relativeto each other and, in fact, could obviously be structurally separate. Each conduit includes cross flow passageways and the conduit 16 includes the passageway 19 which is so positioned in thelue chamber or similar construction that it takes the utmost advantage ot' the radiant heat of such associated structure and at the same time shields the material forming the other conduit from the destructive effect of such heatf while, in the illustrated form, the passage of the air through the counter flow sections extending throughout the main part of the apparatus enables the utmost advantage to be taken of the convected heat of the flue gases. The provision of an inlet f for each passage or conduit enables the separate streams. of air to be individually Acontrolled by any suitable mechanism such, for example, as that disclosed in my copending applications, Serial Nos. 41,135 and 100,862 filed July 2, 1925 and April 9, 1926, respectively. By the use of such a type of control the characteristic of flow of the stream through the conduit including the passageway19 can be maintained sub-S stantially constant irrespective oi variations in the total flow of air through the apparatus and thus the material at the hottest part of the apparatus can be kept at a. temperature within safe limits. The two streams of air mingle in the outlet duct below the baille 13 and emerge through the outlet 14 as a s1ngle stream.

Although I have described a specific form of this invention it will be apparent that vag rious additions, omissions, substitutions and changes can be made therein without departing from the spirit of the invention or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. A heat exchange apparatus having in combination passages for the transmission of fluid to be heated in a direction counter to the direction of flow of the heating gases and arranged in parallel with relation to one another and an inlet for each of said passages.

2. A heat exchange apparatus having in combination passages for the transmission of fluid to be heated in a direction counter to the direction of flow of the heating gases arranged in parallel with relation to one another, an inlet for each of said passages and means for separately controlling the flow through said inlets.

3. A heat exchange apparatus having in combination passages for the transmission of fluid to be heated in a direction counter to the direction of flow of the heating gases arranged in parallel with relation to one another, one of said passages extending through that portion of the apparatus subjected to the ighest temperature and an inlet for each of said passages. l

4. A heat exchange apparatus having in combination a conduit for the passage of fluid to be heated in a direction counter to the direction of flow of the heating gases, a passage located adjacent that part of the apparatus subjected to the highest temperature and communicating with said conduit, a second counter flow conduit, an outlet and a separate inlet for each of said conduits.

A heat exchange apparatus having in combination a conduit for the passage of fluid to be heated in a direction counter to the direction of flow of the heating gases and including a plurality of cross How passages, a passage for the transmission of fluid from said conduit through that part of the apparatus subjected to the highest temperature, 'a second conduit having a plurality of cross flow passages positioned alternately with relation to said first named cross flow passages, an outlet and a separate inlet for each of said conduits so that'the flow through said first conduit can be controlled irrespective of the total low through the apparatus.

6. A heat exchange apparatus havin in combination a counter flow passage inclu ing a number of cross flow sections, a passage communicating therewith and positioned in that end of the apparatus subjected to the highest temperature, a second counter flow passage 5 including cross ow sections alternating with the similar sections of said first passage and means for introducing separate streams of fluid vto be heated to said passages so that the flow through the hottest part of the apparat-us can be control-led irrespective of the total flow through the apparatus.

In testimony whereof, I have hereuntoy subscribed my naine this 2nd day of April, 1926.

GREGORY D. MANTLE. 

